1. Field of the Invention
The present invention relates to scanning and distributing systems for centrally controlled telephone exchanges. Embodiments of the invention are capable of collecting data from various units in an exchange and dispatching orders as needed for operating those units.
2. Description of the Prior Art
A telephone exchange comprises a number of units such as trunk or junctor circuits, dialling receivers, and senders, which intervene episodically in setting up communications so as to provide for signaling, transmission, and reception as they are required.
Roughly, in a telephone exchange control unit computers have a time chart comprising: 1. A first part assigned to scanning - for being informed of conditions of those units and detecting any distinctive event; 2. a second part assigned to distributing orders to the concerned units; and 3. a third part assigned to others tasks and, in particular, to processing data collected during scanning operations so as to derive therefrom orders to be distributed.
In a conventional system, the control unit is helped in scanning and distributing by auxiliary systems which permit optimal use of the control unit time chart by taking over part of the simple operations.
In particular, there is known a system making it possible to scan the units per groups of the same type, one point in each unit of a group being simultaneously scanned simultaneously with similar points of other units of the same group so that a single address provides activation of those points and that scanning result for those points is sent to the control unit in the form of one word, each bit of which corresponds to a unit.
It is also known to sequentially scan similar point of the unit groups of a same type, the scanning system deriving the sequential addresses of the units groups in a same type from the first address delivered by the control unit as well as the number of sequential addresses and the operation code determining the points to be scanned according to their function.
However, such systems have certain drawbacks due to the fact that the groups of units of the same type have sequential addresses which require a carefully structured lay-out of the units within the exchange. But, for a large telephone exchange, full capacity is not provided initially, the exchange being generally formed of only a part of its ultimate equipment at installation time. While it is possible to plan future traffic, it is not possible to accurately plan what equipments will later to be installed, equipment needs when growth occurs being possibly very different from those planned. As a result, it is not easy to provide a complete layout which will fill the needs for an operational scanning system very far in the future.
Thus, a purpose of the present invention is to provide for a scanning and distributing system, such as is referred to above, which is sufficiently flexible to adapt to future growth and changes, with respect to unit layout and programming.